some advice on what size fin would be optimum (many variables) for my 122 and a 9m sail knowing that i&#39;m 120kg+? 46-48 are what i&#39;m looking at. I generally sail overpowered, and early planning is not really the issue, it is more the size of fin matching the sail and my size?

If you&#39;re sailing overpowered on 9m/120kg/iS122 then the fin loads are going to be rather hi. For optimum performance in this mode you should try fins with less flex than normal, sizes 46-48 will be OK for medium powered 9m or something 42-44 for more fully/overpowered especailly if your board speed is high (flatter water)

Stock fins are fine for average use, but realistically these are optimised for typical rider loadings, which delivers better more accesible "mid load" performance.

If your are overpowered then your massive weight could snap the fin. For optimum performance in this potentional hazardous state you should have a steel fin., sizes 46-48 will still probably break as your load is something found on the axel of a race car. something smaller will deliver tons of spin out for bulk but wont break.

Stock fins are made for people who don&#39;t live at Mcdonalds. They are for people who concider their day to day well being and are in fact excellent for that type of healthy minded person.

thanks ian i think,
when i say i sail overpowered, i mean that i generally have bigger everything relative to everybody else and required more board, fin and sail. . So, i&#39;m a bit miffed with your answer as you mention that i actually need a smaller fin than what i suggested , won&#39;t that lead to excessive spinout?